diff --git a/trunk/src/app/srs_app_rtc_conn.cpp b/trunk/src/app/srs_app_rtc_conn.cpp
index bc379927b..364d4b6c2 100644
--- a/trunk/src/app/srs_app_rtc_conn.cpp
+++ b/trunk/src/app/srs_app_rtc_conn.cpp
@@ -543,8 +543,8 @@ srs_error_t SrsRtcPlayStream::cycle()
 
     // TODO: FIXME: Add cost in ms.
     SrsContextId cid = source->source_id();
-    srs_trace("RTC: start play url=%s, source_id=[%d][%s], realtime=%d, mw_msgs=%d", req_->get_stream_url().c_str(),
-        ::getpid(), cid.c_str(), realtime, mw_msgs);
+    srs_trace("RTC: start play url=%s, source_id=%s/%s, realtime=%d, mw_msgs=%d", req_->get_stream_url().c_str(),
+        cid.c_str(), source->pre_source_id().c_str(), realtime, mw_msgs);
 
     SrsErrorPithyPrint* epp = new SrsErrorPithyPrint();
     SrsAutoFree(SrsErrorPithyPrint, epp);
diff --git a/trunk/src/app/srs_app_rtc_source.cpp b/trunk/src/app/srs_app_rtc_source.cpp
index 5dc059adb..bc7c8b93e 100644
--- a/trunk/src/app/srs_app_rtc_source.cpp
+++ b/trunk/src/app/srs_app_rtc_source.cpp
@@ -187,7 +187,7 @@ srs_error_t SrsRtcConsumer::dump_packets(std::vector<SrsRtpPacket2*>& pkts)
     srs_error_t err = srs_success;
 
     if (should_update_source_id) {
-        srs_trace("update source_id=%s[%s]", source->source_id().c_str(), source->source_id().c_str());
+        srs_trace("update source_id=%s/%s", source->source_id().c_str(), source->pre_source_id().c_str());
         should_update_source_id = false;
     }
 
@@ -356,10 +356,7 @@ srs_error_t SrsRtcStream::on_source_id_changed(SrsContextId id)
 
     if (_pre_source_id.empty()) {
         _pre_source_id = id;
-    } else if (_pre_source_id.compare(_source_id)) {
-        _pre_source_id = _source_id;
     }
-
     _source_id = id;
 
     // notice all consumer
@@ -472,6 +469,9 @@ void SrsRtcStream::on_unpublish()
     is_created_ = false;
     is_delivering_packets_ = false;
 
+    if (!_source_id.empty()) {
+        _pre_source_id = _source_id;
+    }
     _source_id = SrsContextId();
 
     for (size_t i = 0; i < event_handlers_.size(); i++) {
diff --git a/trunk/src/app/srs_app_source.cpp b/trunk/src/app/srs_app_source.cpp
index 1147f6a15..3d317eb2d 100755
--- a/trunk/src/app/srs_app_source.cpp
+++ b/trunk/src/app/srs_app_source.cpp
@@ -2555,10 +2555,10 @@ void SrsSource::on_unpublish()
     srs_trace("cleanup when unpublish");
     
     _can_publish = true;
-    _source_id = SrsContextId();
     if (!_source_id.empty()) {
         _pre_source_id = _source_id;
     }
+    _source_id = SrsContextId();
 
     // notify the handler.
     srs_assert(handler);